1. Field of the Invention
This invention relates to burnpits for disposal by combustion of gaseous and liquid hydrocarbons, including light and heavy hydrocarbons with substantial smoke reduction.
2. Description of the Prior Art
It has heretofore been proposed to employ burnpits, usually rectangular in shape, excavated at the surface of the ground and surrounded by dikes of earth or refractory material.
One common form of burnpit comprised a rectangular pit with a substantially flat bottom and with a fluid hydrocarbon delivery pipe extending through one end wall or dike with an unprotected replaceable tip in the combustion space. The tips and pipe due to flame impingement and exposure were quickly destroyed. Serious difficulties and poor performance were encountered with this type of pit because of its tendency to establish an outer combustion zone surrounding an inner evaporation zone. The evaporation zone was starved for oxygen to support combustion so that large quantities of unburned hydrocarbons were vaporized and moved upwardly producing very heavy smoke which discharged into the atmosphere with resultant pollution problems. The heavy smoke at the center blocked the heat from the combustion zone and further aggravated the difficulties. The poor operation resulted in banning the use of burnpits in many places. Most of these burnpits had no pilots or ignition system which required the operating personnel to manually light the waste streams by whatever methods they could improvise.
In addition, if the wind direction was in the opposite direction from that of the discharge of hydrocarbons from the supply pipe the turn back of the flame quickly resulted in destruction of the pipe tip and of exposed portions of the pipe.
If liquid hydrocarbon discharging from the burner tip was blown back under the tip the heat from the burning quickly destroyed the burner tip.
In U.S. Pat. No. 2,462,822 the burning of a combustible medium such as gasoline on the surface of water contained in concrete gutters along the sides of an airfield is illustrated for dispersing of fog and lighting up the landing field. No effective combustion of large quantities of hydrocarbons for disposal is contemplated nor can it be accomplished in that structure.
The British Patent to Bateman, No. 4787 of 1915 shows a rectangular pit for destruction of night soil on a horizontal perforated plate within the pit. No provisions are made for continuous supply of fluid hydrocarbons.
In U.S. Pat. No. 3,749,546 to Reed et al., a pit surrounded by a dike is shown for burning hydrocarbon gas with staged combustion with a multiplicity of gas burners carried at a considerable height on vertical pipes so that there will be a continuing supply of air from beneath the burners to mix with the gas for combustion. Pilots are not shown but are said to be needed.
No horizontal introduction of fluid hydrocarbons into a burnpit through protected piping is shown nor is any attempt made to divide or direct a horizontally directed flame or supply air thereto.
In U.S. Pat. No. 3,822,983 to Proctor et al., a ground flare is shown with a central elongated flat bottom combustion zone surrounded by side and end walls of an earthen bank lined internally with a course of stone, rock, brick or the like, or of refractory material. Along each side and at the bottom of the side walls and transversely to the longitudinal axis of the floor, horizontal parallel tubes set in concrete are provided to supply primary air for combustion. The combustible gas to be burned is delivered through a manifold 17 beneath the floor and through a pair of diverging rows of nozzles into the combustion zone. Steam manifolds are provided in a bed of sand below the aggregate floor and are connected in some manner which is not shown to air moving devices on some of the gas delivery nozzles.
The structures heretofore available have not proven satisfactory for various reasons including poor combustion with high smoke output, lack of adequate protection of burners, pilots, igniters, and piping therefor, lack of availability for other than gaseous hydrocarbons, and other shortcomings.